1. Field Of The Invention
The present invention relates to a method and apparatus for hot stamping foil material to flexible plastic drinking cups and the like. Even more particularly, the present invention relates to an improved method and apparatus for hot stamping plastic cups with foil wound upon a roll wherein during printing, the cup side wall is flattened to receive printed material which is then properly proportioned once the cup is removed from the apparatus and returned to its original shape.
2. General Background
Plastic drinking cups are commercially available in various sizes such as for example eight ounce, twelve ounce, sixteen ounce, twenty-four ounce, thirty-two ounce, and the like. These plastic cups are sold at fast food restaurants and convenience stores for containing soft-drink products, distributed through super markets to end users, and supplied by novelty companies to clubs and organizations with desired printed material thereon. It is known to supply such plastic cups with multi-colored emblems.
A decorative material that is added to plastic cups can be a foil that is placed on the cup using a hot stamping process. As part of this process, the foil like material is contained on a long web wound upon a roll. However, in any attempt to print upon a frustro-conically shaped cup, distortion of the line of type or emblem would limit hand-printing by businesses such as gift shops and card shops. An example of applying foil using hot stamping is seen in U.S. Pat. No. 3,585,093, incorporated herein by reference.
Hand printing is done almost exclusively on flat surfaces. The curved "horseshoe" type die could possibly be used for hand printing on curved surfaces, but the amount of wrap around the circumference could be more limited than with our method due to a scuffing/scraping action at the edges of the die. These dies are expensive also. Another limiting factor is the lack of appropriate supporting devices (mandrels) for existing machines.
Various devices have been patented which are directed to the concept of hot stamping various objects including molded plastic containers. U.S. Pat. No. 1,406,538 discloses roll leaf stamping for decorating book covers and leather goods. An example is U.S. Pat. No. 4,343,670 entitled "Apparatus and Process for Hot Stamping Containers". In the '670 patent, the container is moved past a heated die with a platen carrying a printing die, the die being floatably movable so that linear uniform pressure is exerted between a confronting container surface and die surface. As the container moves across the die surface, it is rotated so that the foil which is pinched between the container and die is transferred onto the surface of the rotatable container. The uniform linear pressure between container and die, transfers foil to the accompaniment of rotation of the container so that defect-free lamination of foil is transferred onto the container surface to form decorative or alphanumeric information. This process relies upon a "controlled force matrix". The operation is continuous, with successively spaced containers moving into printing position relatively to the die, where the hot stamping operation is repeated. Containers are automatically removed after printing, and successive containers supplied either manually or automatically. FIGS. 9 and 10 of the '670 patent show views of the container and mandrel under pressure to maintain linear contact.
The Warsager patent 3,634,174 entitled "Machine For Surface Decorating of Articles" relates to the transfer of a decorative foil from a carrier tape to an object using pressure and heat in which the object can be round or flat. The machine can be used for moving the object vertically into the die or the die can be moved vertically across the object. Another Warsager patent which relates to hot stamping is U.S. Pat. No. 3,657,053 entitled "Mechanism For Rigidifying A Collapsible Object".
The Robertson patent 4,175,993 relates to a method and apparatus for applying indicia to the surface of generally cylindrical articles such as bottles. The patent is entitled "Article Decorating Machine and Method". The machine disclosed in the '993 patent utilizes a rotary article transport assembly or turret mechanism which has a plurality of gripper hands mounted thereon for holding the cylindrical articles to be decorated. At least one article orienting station is provided to orient the article so that the indicia is applied over the proper portion of the surface of the article. After orienting, the article is rotated in a holding assembly and the indicia carrying tape or foil is pressed against the appropriate portion of the outer surface of the article by a heated die carried on a cylindrical drum mounted immediately adjacent to the article being decorated. Means are provided for rotating the article being decorated and the die carrying drum at the same peripheral surface speed. Also, means are provided for positively feeding the decorating tape between the bottle and the transfer die. Another patent that relates to embossing foil to a portion of a flexible web of material is the Mitsam patent 4,701,235 entitled "Method For Applying an Embossing Foil To A Flexible Material".
In the Britt patent 3,585,093 entitled "Method and apparatus For Applying Metal Foil", the metal foil is coated with an adhesive bonding agent for securing it to the surface of an article. The metal foil is pressed against the surface with the adhesive in contact with the surface while the foil is at ambient temperature, then causing the metal foil to adhere to the surface by the application of a heat pulse for a short period of time. Then the coated surface is allowed to cool while maintaining pressure thereon.
Another patent that relates to a hot stamping machine for transferring a decorative material to an article is seen in the Warsager patent 3,657,054 entitled "Decorating Machine For Transferring A Decorative Material to An Article".
The Harvey patent 4,806,197 relates to an apparatus for decorating the cylindrical surface of an article, such as a bottle with a label.
A method and apparatus for hot stamping cylindrical articles such as a hollow plastic bottle is disclosed in the Robertson patent 3,816,207.
The Berg patent 3,718,517 entitled "Method and Apparatus For Decorating Articles" relates to the decorating of the outer surface of an article or wear wherein the article is initially positioned on a holding mandrel mounted to a rotary table while at a loading station. The article is subsequently advanced to a decorating station where a layer of transfer material is interposed between the article and a printing die. The transfer material is caused to engage the article being decorated with the die being moved across the outer surface thereof whereby a portion of the transfer material is caused to adhere to the article.
None of these prior art patented systems uses an arcuate type, distorted for correction of a frustro-conical cup, and/or wherein the cup wall is flattened during printing. All require rigidifying the container.